Apple agreed to limit the term of one of the patents it used to win a $1.05 billion jury verdict against Samsung. The company filed a so-called "terminal disclaimer" with the patent office today. It limits the term of patent D618,677, a patent that 12 different Samsung phones were found to infringe.

It's not much of a sacrifice. By filing the disclaimer, Apple now links its D'677 patent to the term of an earlier patent, No. D593,087. In doing so it's giving up about 13 months of patent life. Both patents will now expire in May 2023. (This paragraph was edited after publication to reflect the fact that design patents expire 14 years from issuance.)

The idea appears to be to cut off one of Samsung's post-trial arguments. Samsung argued that notwithstanding the jury verdict, Apple's design patents are invalid for a number of reasons; in particular, it argues that the D'677 patent is invalid for so-called "double patenting." In other words, the D'087 and the D'677 patents are too similar to be granted separate patents.

Today's move suggests Apple feels at least a bit threatened by that argument. It's not hard to understand why; the patent drawings do look very similar.

As Samsung writes in its post-trial motion [PDF]: "D’677 and embodiments of D’087 (particularly the sixth embodiment) depict the same design; the only elements added by the D’677 are the color black and oblique lines, features that do not make D’677 “a separate invention, distinctly different and independent.""

However, the argument Apple hopes to kick out here is only one of three separate arguments that Samsung presents as to why the D'677 should be invalidated. And in any case, Samsung's entire post-trial brief needs to be considered a longshot. Samsung is arguing from a position of weakness, suggesting the judge should second-guess the jury's verdict. Such victories surely do happen, but they're rare.

If the D'677 patent were actually invalidated, that would be a real blow to Apple's case, although it's not clear how highly the judge would value that particular patent. (The jury didn't break out damages on a patent-by-patent basis.)

The next major step in the case is a December 6 hearing on both sides' post-trial motions.